Since the antigen-antibody reaction is a highly-specific reaction, it is applied to the detection or the like of specific proteins and the like. For example, ELISA is a method of detecting antigens (proteins and the like) as follows. That is, an antibody labeled with an enzyme is allowed to react with a specific antigen (protein or the like) in a sample to form a complex, the complex is captured by an antigen immobilized to a bead or the like, and a chromogenic substrate is allowed to act on the enzyme. Further, antibodies are used as medicines utilizing their specificity (for example, see Patent Document 1).
As detection reagents, antibodies derived from rodents such as mice and rats are used. In a detection kit using a rodent-derived antibody, an antigen that specifically binds to a rodent-derived antibody is used. However, there are problems that the production of antibodies is difficult and the handling of antibodies is complicated.